The ultimate goal of this research program is to determine the chemical structure and biological function of the nonhistone chromosomal proteins (NHC proteins) of Drosophila. Particular emphasis will be placed on studying heterogeneity of these proteins, their role in maintaining chromatin structure, and their role in the general mechanism of gene activation. Initial work aims at the isolation and chemical characterization of the NHC proteins and histones; concurrently, antibodies are being made to the total and isolated chromosomal proteins. The use of labeled antibody techniques to provide specific "stains" for the NHC proteins will allow one to answer many important questions concerning the distribution and role of the NHC proteins in vivo. The information and techniques developed, coupled with information on enzymic properties on NHC protein, will provide the means to start to trace the sequence of biochemical events in the gene activation as it occurs in the salivary gland polytene chromosomes of Drosophila in response to hormone stimuli, heat shock, etc. BIBLIOGRAPHIC REFERENCES: Elgin, S.C.R. and Miller, D.W. (1976) "Preparation of Nuclei, Chromatin, and Chromosomal Proteins of Drosophila Embryos," in The Genetics and Biology of Drosophila 2, ed. Ashburner, M. and Wright, T.R.F. (Academic Press, N.Y.) in press. Silver, L.M. and Elgin, S.C.R. (1976) "A Method for Determination of the in situ Distribution of Chromosomal Proteins," Proc. Nat. Acad. Sci. USA 73, 423-27.